More than 100 personnel, along with rescue gear, dogs and aid supplies, are being flown on military transport planes from Australia and New Zealand to the stricken capital Port Vila.
The 7.3-magnitude quake struck off the Pacific nation's main island on Tuesday, flattening multi-storey concrete buildings, cracking walls and bridges, damaging water supplies and knocking out most mobile networks.
Vanuatu has declared a seven-day state of emergency "due to the severe impacts", along with a curfew from 6 pm-6 am.
Civilians joined in the immediate rescue effort despite multiple aftershocks shaking the low-lying archipelago of 320,000 people, which lies in the quake-prone Pacific Rim of Fire.
AFP photos showed rescuers working with mechanical diggers at night to save people in one large building, all its floors pancaked into a flat pile of concrete.
Rescuers were focused on searching for people in two collapsed buildings in Port Vila, said Glen Craig of the Vanuatu Business Resilience Council.
"We know people are trapped and some have been rescued, and there have also been fatalities," he told AFP.
"My good friend that was killed in the earthquake -- the funeral is at 2 pm today -- but I have also got to think about the other 300,000 people in Vanuatu," Craig said.
Australia's government flew in a 64-person disaster response team equipped with two dogs, along with six medics, nine police and emergency response managers.
Death toll set to rise
"Australia's emergency crews are now on the ground in Vanuatu following the devastating earthquake," said Foreign Minister Penny Wong.
A government-organised flight has also repatriated 61 Australians, she said.
New Zealand is flying in a 36-strong rescue team, government officials said. A separate C-130 military transport plane with rescue equipment and disaster supplies landed on Thursday.
Nine people have been confirmed dead by Port Vila's hospital and that number is likely to rise, according to the latest update by Vanuatu's disaster management office.
The quake caused "major structural damage" to more than 10 buildings including the main hospital, it said, while also hitting three bridges, power lines, water reserves and mobile communications.
The shipping port is closed following a "major landslide".
French engineers have declared Port Vila's airport runway operational, although it has not re-opened to civilian flights.
The death toll will "definitely go up", said Craig, of the Vanuatu business council.
However the country and its people depended on tourism and agriculture, he warned.
'People need to come back'
"We can't have an economic disaster on top of a natural disaster," Craig said, urging a quick restart of the tourism business.
"The runway is in great condition and it has been a huge focus for the government to get that terminal open by tonight or latest tomorrow for commercial flights," he said.
"People need to come and go, it brings normality back."
Craig said he had visited four resorts, which were using generators for electricity and hoping for tourists to return next week.
"Generally, they are okay, there are some cracks and some tiles have popped out, but there is not bad damage."
Basil Leodoro, an emergency doctor in Vanuatu with Respond Global, said landslides blocked airfields on some surrounding islands, raising concerns about food supplies.
Water supplies, including wells and storage systems, were damaged on some islands, he told AFP.
Earthquake injuries were only being reported on the main island of Vanuatu, however.
"As expected, we are seeing open fractures, wounds and closed fractures, soft tissue injury as a result of the earthquake," Leodoro said.
He said he was helping to organise medical support from Fiji and Solomon Islands to relieve exhausted teams in Vanuatu.
"That is the burden we are seeing -- it is not unexpected in these crisis situations."
